Breeding Systems
AgriScience 2
Animal Reproduction
Why is improving organisms
important to agriculture?
• Three main factors driving this goal:
– Rising World Population
– Urbanization
– Fewer people in production agriculture
What methods are used in agriscience to
improve organisms?
• Two major approaches are used:
– Controlled breeding
– Genetic manipulation.
Controlled breeding
• Breeding plants or animals to achieve
certain characteristics in the offspring.
• Considered a natural method of improving
plants and animals.
– Scientists control the natural breeding process.
Kinds of controlled breeding:
• Selection
– Choosing a few parents with the desired traits with
the intent of increasing the amount of desired
qualities in the offspring.
Genetic manipulation
• Artificial means of producing desirable
traits.
• Genes can be moved from one species to
another.
• Gene splicing is the moving of hereditary
characteristics from one organism to
another often unrelated organism.
Hybridization
• Crossing of two different plants or animals
• Combines the traits of different parent
strains.
• Many hybrids are not able to reproduce.
Straight breeding
• Inbreeding• close breeding
• purebreeding
Inbreeding-mating closely related
animals
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Parent to offspring and siblings
1/2 brother and sister
12.5% inbred
Uncle x niece
Nephew x aunt
6.25% inbred
1/2 uncle to niece
Cousin to cousin 3.125% inbred
25% inbred
Closebreeding- mating animals
that share some common
ancestors
Purebreeding- mating animals
that are not related but of the
same breed.
Crossbreeding- mating animals of
different breeds.
Crossbreeding Systems
Cross breeding- Criss-Cross
F1 - 1/2 B 1/2 L
Criss-cross
Brahman
F1 1/2B 1/2L
F2 1/4L 3/4 B
Criss-Cross
Limousin
F2 3/4B 1/4L
F2 5/8L 3/8 B
Rotational Breeding-1st Cross
Columbia
Dorset
F1 - 1/2 C 1/2 D
Rotational Breeding-2nd Gen
Hampshire
F1- 1/2C 1/2 D
F2 - 1/4 C 1/4 D
1/2 H
Rotational- 3rd Generation
F2 - 1/4 C 1/4
D 1/2 H
Dorset
F3 - 1/8 C 1/4 H 5/8 D
Rotational Breeding
Terminal Cross
Roto-Terminal Cross
Roto-Terminal Cross
3 breed roto cross
Hampshire Terminal boar
1/2 Hamp, 1/2 white blend
Review / Summary
• Discuss the importance of improved
organisms to agriculture.
• Identify methods used in agriscience to
improve organisms.
• Identify breeding systems used in animal
science.